RE: JVP 27(1)

[Tim Williams <twilliams_alpha@hotmail.com>]

Justin Tweet wrote:

> Butler, Richard J., and Upchurch, Paul. 2007. Highly incomplete taxa and 
> the phylogenetic relationships of the theropod dinosaur Juravenator starki. 
> 253-256.
>
> A priori removal of seven taxa in the original description's tree (Göhlich 
> and Chiappe, 2006) was
> unjustified, and their results thus donot support Juravenator as a 
> compsognathid, but they do support a basal maniraptoran position.

Butler and Upchurch's analysis does give the theropod tree a good shake.  
They do a lot more than simply dumping _Juravenator_ at the base of the 
Maniraptora.  For example...

(1) _Allosaurus_, _Sinraptor_ and tyrannosaurids are recovered as a clade to 
the exclusion of coelurosaurs.  This clade would fit Holtz's (2004) 
definition of Carnosauria.  So, this analysis puts the Tyrannosauridae back 
among the carnosaurs!  The Bremer support was weak, however.  Also, only two 
derived tyrannosaurid taxa were used (_Albertosaurus_ and _Tyrannosaurus_), 
thus emphasizing the value of including basal taxa.

(2) An alvarezsaurid-therizinosauroid-oviraptorosaur clade pops up.  This 
was recovered as the sister taxon to the Deinonychosauria-Aves clade.

(3) The analysis finds a _Compsognathus_-_Coelurus_ clade (Compsognathidae), 
that excludes not only _Juravenator_ (basal maniraptoran) but also 
_Sinosauropteryx_ and _Huaxiagnathus_ (both more derived than 
_Compsognathus_).

(4) _Coelophysis_ and _Dilophosaurus_ are recovered as consecutive outgroups 
to the Tetanurae.  However, _Ceratosaurus_ and abelisaurids are conspicuous 
by their absence.  (This could have impacted on (1) as well).

Cheers

Tim

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